CN115113007A - Device and method for evaluating insulating property of anticorrosive coating of pipeline at crossing section of directional drill - Google Patents
Device and method for evaluating insulating property of anticorrosive coating of pipeline at crossing section of directional drill Download PDFInfo
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- 238000000576 coating method Methods 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 17
- 230000007246 mechanism Effects 0.000 claims abstract description 48
- 238000011156 evaluation Methods 0.000 claims abstract description 30
- 238000005553 drilling Methods 0.000 claims abstract description 18
- 230000007797 corrosion Effects 0.000 claims description 11
- 238000005260 corrosion Methods 0.000 claims description 11
- 238000012360 testing method Methods 0.000 claims description 8
- 238000012935 Averaging Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 229910000365 copper sulfate Inorganic materials 0.000 description 3
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 3
- 238000004210 cathodic protection Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 239000011435 rock Substances 0.000 description 1
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- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
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Abstract
The invention discloses an insulating property evaluation device for an anticorrosive coating of a pipeline at a crossing section of a directional drill, which comprises a first measuring mechanism, a second measuring mechanism, a direct-current power supply, a current interrupter and a temporary auxiliary anode, wherein the first measuring mechanism and the second measuring mechanism are respectively arranged at the first end and the second end of the pipeline at the crossing section, the measuring mechanisms are used for acquiring on-off potentials and on-off currents at the two ends of the pipeline at the crossing section, the negative electrode of the direct-current power supply is connected with the pipeline at the non-crossing section connected with the second end of the pipeline at the crossing section, the positive electrode of the direct-current power supply is connected with the current interrupter, and the current interrupter is connected with the temporary auxiliary anode. The invention also discloses a method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drilling by using the evaluation device. The device and the method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill can evaluate the insulating property of the anticorrosive coating of the pipeline at the crossing section.
Description
Technical Field
The invention relates to the field of pipeline corrosion prevention, in particular to a device and a method for evaluating the insulating property of a corrosion-resistant layer of a pipeline at a directional drilling crossing section.
Background
The horizontal directional drilling technology is a non-excavation technology, has the characteristics of no damage to stratum structures, less construction occupied area, no influence from seasons, short construction period and the like, and is widely applied to the situation that an oil and gas pipeline passes through regions which are not suitable for shallow burying, such as rivers, railways, expressways, mountainous regions and the like. In the back dragging process of the pipeline at the crossing section, due to the influence of factors such as rocks, hard stones and irregular holes, the integrity of an anticorrosive coating is often difficult to maintain, but the anticorrosive coating is used as an important barrier for protecting the pipeline, and the integrity of the anticorrosive coating is related to the service life of the pipeline, so that the problem of how to evaluate the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill is urgently solved in practical engineering.
Disclosure of Invention
The invention aims to provide a device and a method for evaluating the insulating property of an anticorrosive coating of a pipeline at a crossing section by directional drilling, which can evaluate the insulating property of the anticorrosive coating of the pipeline at the crossing section.
The insulating property evaluation device for the anticorrosive coating of the directional drilling crossing section pipeline comprises a first measuring mechanism, a second measuring mechanism, a direct current power supply, a current interrupter and a temporary auxiliary anode, wherein the first measuring mechanism is installed at a first end of the crossing section pipeline, the second measuring mechanism is installed at a second end of the crossing section pipeline, the first measuring mechanism is used for acquiring an electrified potential and an off-potential of the first end and an electrified current and an off-current flowing through the first end, the second measuring mechanism is used for acquiring an electrified potential and an off-potential of the second end and an electrified current and an off-current flowing through the second end, a negative electrode of the direct current power supply is connected with a non-crossing section pipeline connected with the second end of the crossing section pipeline, a positive electrode of the direct current power supply is connected with the current interrupter, and the current interrupter is connected with the temporary auxiliary anode.
The insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drill comprises a first measuring mechanism, a first reference electrode and a first clamp ammeter, wherein the positive electrode of the first voltmeter is connected with the first end of the pipeline at the crossing section, the negative electrode of the first voltmeter is connected with the first reference electrode, the first reference electrode is in contact with the ground, the first clamp ammeter comprises a first measuring clamp and a first ammeter body which are mutually connected, and the first measuring clamp is arranged at the first end of the pipeline at the crossing section in a surrounding manner.
The insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drill comprises a second measuring mechanism, a second reference electrode and a second clamp ammeter, wherein the positive electrode of the second voltmeter is connected with the second end of the pipeline at the crossing section, the negative electrode of the second voltmeter is connected with the second reference electrode, the second reference electrode is in contact with the ground, the second clamp ammeter comprises a second measuring clamp and a second ammeter body which are connected with each other, and the second measuring clamp is arranged at the second end of the pipeline at the crossing section in a surrounding mode.
The method for evaluating the insulating property of the anticorrosive coating of the directional drilling crossing pipeline by using the evaluation device comprises the following steps of:
(1) starting the direct current power supply and switching on and off the current interrupter,
(2) obtaining a penetration by a first measuring mechanismElectrified potential V of first end of cross-section pipeline 1on Power-off potential V 1off Conduction current I 1on And a power-off current I 1off (ii) a Acquiring the electrified potential V of the second end of the pipeline passing through the section through a second measuring mechanism 2on Power-off potential V 2off Conduction current I 2on And a power-off current I 2off ，
(3) To the electrified potential V of the first end of the pipeline of the crossing section 1on And a power-off potential V 1off Differencing to give Δ V 1 ＝V 1on -V 1off To the electrified potential V of the second end of the crossing section pipeline 2on And a power-off potential V 2off Differencing to give Δ V 2 ＝V 2on -V 2off Then to Δ V 1 And Δ V 2 Averaging to obtain the difference between the average power-on potential and the power-off potential of the pipeline passing through the segment
The electrified current I to the first end of the pipeline passing through the section 1on And a power-off current I 1off Differencing to give Δ I 1 ＝I 1on -I 1off Current I to the second end of the crossing section of the pipe 2on And a power-off current I 2off Differencing to give Δ I 2 ＝I 2on -I 2off Then to Δ I 2 And Δ I 1 Obtaining the current leakage I of the pipeline passing through the section by difference sect ＝ΔI 2 -ΔI 1 ，
(4) Obtaining the average resistance of the anticorrosive coating of the pipeline at the crossing section according to ohm's law
(5) The average surface resistivity r of the anticorrosive coating of the pipeline at the crossing section is calculated by using the following formula sect And resistivity r for evaluation under the condition of conversion of 1000 Ω & cm sect@1000Ω·㎝ ，
r sect ＝R sect ×A s
A s ＝πdL
Wherein ρ is test D is the outer diameter of the pipeline at the crossing section, L is the length of the pipeline at the crossing section,
(6) then calculating to obtain the average conductivity of the anticorrosive coating of the pipeline at the crossing section
(7) According to the average conductivity or resistivity r of the anticorrosive coating of the pipeline at the cross section sect@1000Ω·㎝ And determining the insulating property of the anticorrosive coating of the pipeline at the crossing section.
The insulating property evaluation method of the directional drilling crossing section pipeline anticorrosive coating by using the evaluation device in the invention, wherein in the step (3), the potential difference ratio of the crossing section pipeline
And (3) the K value is between 0.625 and 1.6, otherwise, the pipeline at the crossing section is divided into more than two sub-crossing section pipelines, and then the insulating property of the anticorrosive coating of each sub-crossing section pipeline is evaluated according to the steps (1) to (7).
The device and the method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill are different from those of the prior art in that the insulating property of the anticorrosive coating of the pipeline at the crossing section is determined by starting a direct-current power supply and performing on-off operation on a current interrupter, acquiring the electrifying potential, the power-off potential, the electrifying current and the power-off current of the first end of the pipeline at the crossing section through a first measuring mechanism, acquiring the electrifying potential, the power-off potential, the electrifying current and the power-off current of the second end of the pipeline at the crossing section through a second measuring mechanism, calculating the average conductivity or resistivity of the anticorrosive coating of the pipeline at the crossing section according to the acquired electrifying potential and power-on current, and finally determining the insulating property of the anticorrosive coating of the pipeline at the crossing section according to the average conductivity or resistivity of the anticorrosive coating of the pipeline at the crossing section. Therefore, the method can evaluate the insulating property of the pipeline anticorrosive coating at the crossing section.
The invention will be further explained with reference to the drawings.
Drawings
FIG. 1 is a first use state diagram of the insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drill in the invention;
FIG. 2 is a second use state diagram of the insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drilling machine in the invention;
fig. 3 is a flow chart of the method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill in the invention.
Detailed Description
As shown in fig. 1, the device for evaluating the insulating property of the corrosion protection layer of the directional drilling crossing segment pipeline in the invention comprises a first measuring mechanism, a second measuring mechanism, a dc power supply 8, a current interrupter 9 and a temporary auxiliary anode 10, wherein the first measuring mechanism is installed at a first end (namely, the left end in the figure) of the crossing segment pipeline 13, the second measuring mechanism is installed at a second end (namely, the right end in the figure) of the crossing segment pipeline 13, the first measuring mechanism is used for acquiring an energization potential and a power-off potential of the first end and an energization current and a power-off current flowing through the first end, the second measuring mechanism is used for acquiring an energization potential and a power-off potential of the second end and an energization current and a power-off current flowing through the second end, the negative electrode of the dc power supply 8 is connected with a non-crossing segment pipeline 11 connected with the second end of the crossing segment pipeline 13, the positive electrode of the dc power supply 8 is connected with the current interrupter 9, the current interrupter 9 is connected to a temporary auxiliary anode 10.
It should be noted that, there is a leakage point of the anticorrosive coating on the cross-over section pipe 13, and when the current interrupter 9 is in the closed state, the current applied by the dc power supply 8 can enter the soil 4 from the positive electrode of the dc power supply 8 through the current interrupter 9 and the temporary auxiliary anode 10, and then flow into the cross-over section pipe 13 from the leakage point of the anticorrosive coating, and flow back to the negative electrode of the dc power supply 8.
As shown in fig. 1, a first end of the cross-section pipe 13 is disposed away from the dc power supply 8, and a second end of the cross-section pipe 13 is disposed close to the dc power supply 8. When the current interrupter 9 is in the on state, there is a steady current flow from the first end to the second end of the cross section pipe 13, so that the cross section pipe 13 achieves temporary cathodic protection.
The dc power supply 8 may be a rectifier or potentiostat. The rectifier is a device for converting alternating current into direct current and can be used for supplying power; the potentiostat can belong to a branch under the rectifier and has the functions of constant potential and constant current.
As for the current interrupter 9, the current interrupter 9 is a device that can be turned on and off, and is used in series with the dc power supply 8, and can be turned on and off periodically in a current loop applied by the dc power supply 8.
For the temporary auxiliary anode 10, the temporary auxiliary anode 10 is used in cooperation with the dc power supply 8 as an anode for temporary cathodic protection. The temporary auxiliary anode 10 may be a ground bed, or may be a metal or an alloy, and is not particularly limited in the embodiment of the present invention.
The insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drill comprises a first voltmeter 3, a first reference electrode 2 and a first clamp ammeter, wherein the positive electrode of the first voltmeter 3 is connected with the first end of the pipeline 13 at the crossing section, the negative electrode of the first voltmeter 3 is connected with the first reference electrode 2, the first reference electrode 2 is in contact with the ground, the first clamp ammeter comprises a first measuring clamp 14 and a first ammeter body 1 which are connected with each other, and the first measuring clamp 14 is arranged at the first end of the pipeline 13 at the crossing section in a surrounding mode.
The first reference electrode 2, which may be a copper sulfate reference electrode, is inserted directly into the ground and is located directly above the pipe.
The insulating property evaluation device for the anticorrosive coating of the pipeline at the crossing section of the directional drill comprises a second voltmeter 5, a second reference electrode 6 and a second clamp ammeter, wherein the positive electrode of the second voltmeter 5 is connected with the second end of the pipeline 13 at the crossing section, the negative electrode of the second voltmeter 5 is connected with the second reference electrode 6, the second reference electrode 6 is in contact with the ground, the second clamp ammeter comprises a second measuring clamp 12 and a second ammeter body 7 which are connected with each other, and the second measuring clamp 12 is arranged at the second end of the pipeline 13 at the crossing section in a surrounding mode.
The second reference electrode 6, which may be a copper sulfate reference electrode, is inserted directly into the ground and is located directly above the pipe.
As shown in fig. 2, the device for evaluating the insulating property of the corrosion protection layer of the directional drilling traversing segment pipeline in the present invention can also be used for evaluating more than two sub-traversing segment pipelines connected with each other, where two sub-traversing segment pipelines (referred to as a first sub-traversing segment pipeline 131 and a second sub-traversing segment pipeline 132) are taken as an example for explanation, each sub-traversing segment pipeline is equipped with a set of evaluation device, the dc power supply 8, the current interrupter 9, the temporary auxiliary anode 10, and the first measurement mechanism and the second measurement mechanism at two ends of the first sub-traversing segment pipeline 131 together form a first set of evaluation device, and the first set of evaluation device is used for evaluating the first sub-traversing segment pipeline 131; the dc power supply 8, the current interrupter 9, the temporary auxiliary anode 10, and the second and third measuring mechanisms at the two ends of the second sub-cross-section pipe 132 together form a second set of evaluation device, which is used for evaluating the second sub-cross-section pipe 132. In actual operation, only one measuring mechanism, namely a second measuring mechanism, is arranged between the two sub-crossing sections of the pipelines 131 and 132, and the second measuring mechanism belongs to both the first set of evaluation device and the second set of evaluation device; meanwhile, only one of the direct current power supply 8, the current interrupter 9 and the temporary auxiliary anode 10 is provided, and the direct current power supply 8, the current interrupter 9 and the temporary auxiliary anode 10 belong to the first set of evaluation device and the second set of evaluation device.
The first end and the second end of the first sub-cross-section pipe 131 are respectively the left end and the right end shown in fig. 2, and the first end and the second end of the second sub-cross-section pipe 132 are respectively the left end and the right end shown in fig. 2, and since the right end (the second end) of the first sub-cross-section pipe 131 is connected with the left end (the first end) of the second sub-cross-section pipe 132, the second end of the first sub-cross-section pipe 131 is also the first end of the second sub-cross-section pipe 132. The first measuring mechanism is installed at the first end of the first sub-cross-section pipe 131, the second measuring mechanism is installed at the second end of the first sub-cross-section pipe 131 and the first end of the second sub-cross-section pipe 132, and the third measuring mechanism is installed at the second end of the second sub-cross-section pipe 132.
The third measuring mechanism has the same structure as the first measuring mechanism and the second measuring mechanism, the third measuring mechanism includes a third voltmeter 15, a third reference electrode 16 and a third clamp ammeter, the positive electrode of the third voltmeter 15 is connected with the second end of the second sub-crossing section pipeline 132, the negative electrode of the third voltmeter 15 is connected with the third reference electrode 16, the third reference electrode 16 is in contact with the ground, the third clamp ammeter includes a third measuring clamp 18 and a third ammeter body 17 which are connected with each other, and the third measuring clamp 18 is arranged around the second end of the second sub-crossing section pipeline 132. The third reference electrode 16, which may be a copper sulfate reference electrode, is inserted directly into the ground and is located directly above the pipe.
As shown in fig. 2, for the first set of evaluation devices of the first sub-cross-section pipe 131, the negative electrode of the dc power supply 8 is connected to the non-cross-section pipe 11, and the non-cross-section pipe 11 is connected to the second end of the first sub-cross-section pipe 131 through the second sub-cross-section pipe 132, so that the negative electrode of the dc power supply 8 is also connected to the non-cross-section pipe 11 connected to the second end of the first sub-cross-section pipe 131.
It should be noted that, the clamp-on ammeter is the prior art, and when in use, the measuring clamp is disposed around the outside of the circuit to be measured, and when the circuit to be measured passes through the current, the magnitude of the current is displayed on the ammeter body, and the working principle of the clamp-on ammeter is not described again.
As shown in FIG. 3, the method for evaluating the insulating property of the directional drilling crossing section pipeline anticorrosive coating by using the evaluation device comprises the following steps:
(1) the dc power supply 8 is started, and the current interrupter 9 is switched on and off,
(2) the electrified potential V of the first end of the pipeline 13 passing through the section is obtained by the first measuring mechanism 1on Power-off potential V 1off Conduction current I 1on And a power-off current I 1off (ii) a The second end of the pipeline 13 passing through is obtained through a second measuring mechanismElectric potential V 2on Power-off potential V 2off And an energizing current I 2on And a power-off current I 2off ，
(3) The electrified potential V of the first end of the pipeline 13 of the crossing section 1on And a power-off potential V 1off Differencing to give Δ V 1 ＝V 1on -V 1off To the current potential V of the second end of the crossing section pipeline 13 2on And a power-off potential V 2off Differencing to give Δ V 2 ＝V 2on -V 2off Then to Δ V 1 And Δ V 2 Averaging to obtain the difference between the average power-on potential and the power-off potential of the cross-section pipeline 13
Current I to the first end of the pipe 13 1on And a power-off current I 1off Differencing to give Δ I 1 ＝I 1on -I 1off Current I to the second end of the pipe section 13 2on And a power-off current I 2off Differencing to give Δ I 2 ＝I 2on -I 2off Then to Δ I 2 And Δ I 1 Obtaining the current leakage I of the pipeline 13 passing through the section by difference sect ＝ΔI 2 -ΔI 1 ，
(4) Obtaining the average resistance of the anticorrosive coating of the pipeline 13 passing through the section according to ohm's law
(5) The average surface resistivity r of the anticorrosive coating of the pipeline 13 at the crossing section is calculated by the following formula sect And resistivity r for evaluation under the condition of conversion of 1000 Ω & cm sect@1000Ω·㎝ ，
r sect ＝R sect ×A s
A s ＝πdL
Wherein ρ is test D is the outer diameter of the cross-section pipe 13, L is the length of the cross-section pipe 13,
(6) then the average conductivity of the anticorrosive coating of the pipeline 13 at the crossing section is calculated
(7) According to the average conductivity or resistivity r of the anticorrosive coating of the cross section pipeline 13 sect@1000Ω·㎝ And determining the insulating property of the anticorrosive coating of the pipeline 13 at the crossing section.
In the above step (5), A s Is the surface area of the cross-section pipe 13, and has a unit of square meter (m) 2 ) (ii) a Pi is the circumference ratio; d and L are both in meters (m). The average conductivity calculated in the step (6) is the nominal conductivity and has the unit of S/m 2 . In the above process of calculating the average conductivity, the unit of potential is volt (V), the unit of current is ampere (a), the unit of resistance is ohm (Ω), and the unit of resistivity is Ω · m.
The method for evaluating the insulating property of the anticorrosive coating of the directionally-drilled through-segment pipeline by using the evaluation device in the invention is characterized in that in the step (3), the potential difference ratio of the through-segment pipeline 13
And (3) the K value is between 0.625 and 1.6, otherwise, the crossing section pipeline 13 is divided into more than two sub-crossing section pipelines 131 and 132, and then the insulating property of the anticorrosive layer of each sub-crossing section pipeline is evaluated according to the steps (1) to (7).
The device and the method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill are different from those of the prior art in that the insulating property of the anticorrosive coating of the pipeline at the crossing section 13 is determined according to the average conductivity and the resistivity of the anticorrosive coating of the pipeline at the crossing section 13 by turning on the direct-current power supply 8 and switching on and off the current interrupter 9, acquiring the electrifying potential, the power-off potential, the electrifying current and the power-off current of the first end of the pipeline at the crossing section 13 through the first measuring mechanism, acquiring the electrifying potential, the power-off potential, the electrifying current and the power-off current of the second end of the pipeline at the crossing section 13 through the second measuring mechanism, calculating according to the acquired electrifying potential and power-off current, and finally determining the insulating property of the anticorrosive coating of the pipeline at the crossing section 13 according to the average conductivity and resistivity of the anticorrosive coating of the pipeline at the crossing section 13. Therefore, the invention can evaluate the insulating property of the anticorrosive coating of the pipeline 13 at the crossing section.
The following describes a specific use of the present invention in a specific embodiment.
A certain directional drill penetrates through a section of pipeline to be an in-service pipeline, the length of the directional drill of the section of pipeline is 1090m, the pipeline is in the north-south direction, the pipeline is completed in 2017, an anticorrosive layer of the pipeline is 3PE, and the pipe diameter of the pipeline is DN 500.
In the directional drilling crossing section pipeline, a direct current power supply and a temporary anode bed (namely a temporary auxiliary anode 10) are adopted to feed in direct current, the distance between the temporary anode bed and the pipeline is more than 100m, 2 pipeline pits are respectively excavated at the starting point (namely the south end of the crossing section pipeline) and the end point (namely the north end of the crossing section pipeline) of the directional drilling, a clamp-on ammeter is adopted to measure the current flowing through the pipeline when the direct current power supply 8 is switched on and switched off, and the potential of the pipeline when the direct current power supply 8 is switched on and switched off is measured by a voltmeter. And feeding direct current into the pipeline by adopting a direct current power supply and a temporary anode ground bed at the north end of the pipeline at the crossing section.
The direct current fed into the direct current power supply 8 is Ir, and when the current is fed into the pipeline, the current in the pipeline of the south end test point is I 1ON The current in the pipeline of the north test point is I 2ON The potential of the pipeline at the south end measuring point is V 1ON The potential of the pipeline at the north end measuring point is V 2ON When the direct current power supply 8 is turned off, the current in the pipeline of the south end measuring point is I 1OFF The current in the pipeline at the north end measuring point is I 2OFF The potential of the pipeline at the south end measuring point is V 1OFF The potential of the pipeline at the north end measuring point is V 2OFF When the DC power supply 8 is turned on and off, the current difference in the south side pipeline is Delta I 1 The difference between the currents in the north pipeline is Delta I 2 The on-off potential difference of the south pipeline is delta V 1 North of ChinaThe on-off potential difference of the side pipeline is delta V 2 The current absorbed by the pipeline at the crossing section is I, the average on-off potential difference of the pipeline at the crossing section is Delta V, the resistance of an anticorrosive layer of the pipeline at the crossing section is R, the area of the pipeline at the crossing section is A, the resistivity of the anticorrosive layer of the pipeline at the crossing section is R, and the nominal conductivity lambda of the pipeline at the crossing section.
When 2A current is fed into the pipeline, the parameters of the pipeline at the crossing section and the conductivity of the anticorrosive layer are shown in the following table 1, when no power is fed, the current in the pipeline at the south end of the pipeline at the crossing section is 0.304A, the current direction flows from north to south, the pipeline potential is-1.169V, and the current in the pipeline at the north end of the pipeline at the crossing section is 0.490A, and the pipeline potential is-1.231V. When 2A current is fed into the pipeline, the current in the pipeline is 0.253A at the south end measuring point of the pipeline passing through the section, the current direction flows from south to north, and the pipeline potential is-1.392V, and the current in the pipeline is 0.176A at the north end measuring point of the pipeline passing through the section, and the pipeline potential is-1.654V. The resistivity of the anticorrosion layer calculated according to the evaluation method is 964.4 omega.m, the resistivity of the anticorrosion layer is 187.3 omega.m after the anticorrosion layer is normalized to 10 omega.m (namely 1000 omega.cm), and the nominal conductivity of the anticorrosion layer is 5.339 multiplied by 10 -3 S/m 2 . The grade of the corrosion protection layer for a directional drilled through section of pipe was rated 4 according to the rating criteria for conductivity/resistivity of the corrosion protection layer specified by the NACE standard (see table 4).
TABLE 1 test results of a certain directional drill passing through a section of pipeline fed with 2A current
When 0.988A current is fed into the pipeline, the pipeline parameters and the conductivity of the anticorrosive layer are shown in the following table 2, and the resistivity of the anticorrosive layer surface of the pipeline at the directional drilling and crossing section is 921.8 omega m, after the resistivity of the anticorrosive layer is normalized to 10 omega m (namely 1000 omega cm), the resistivity of the anticorrosive layer is 179.0 omega m, and the nominal conductivity of the anticorrosive layer is 5.587 multiplied by 10 -3 S/m 2 . The grade of the corrosion protection layer for a directionally drilled through section of pipe was rated 4 according to the rating criteria for conductivity/resistivity for corrosion protection specified in the NACE standard (see table 4).
TABLE 2 test results of a directional drill passing through a section of a pipe fed with 0.988A current
When 0.588A of current is fed into the pipeline, the pipeline parameters and the conductivity of the anticorrosive layer are shown in the following table 3, the resistivity of the anticorrosive layer surface of the pipeline at the crossing section of the directional drill is 1050.8 omega m, the resistivity of the anticorrosive layer is 204.1 omega m after the resistivity of the anticorrosive layer is normalized to 10 omega m (namely 1000 omega cm), and the nominal conductivity of the anticorrosive layer is 4.900 multiplied by 10 -3 S/m 2 . The grade of the corrosion protection layer for a directional drilled through section of pipe was rated 4 according to the rating criteria for conductivity/resistivity of the corrosion protection layer specified by the NACE standard (see table 4).
TABLE 3 test results of a certain directional drill passing through a section of pipe fed with 0.588A current
The grading standards for corrosion protection layer conductivity/resistivity according to the NACE standard are set forth in the table below.
TABLE 4 grading table for anticorrosive coating of pipeline at crossing section of directional drill
It should be noted that the terms "center", "upper", "lower", "front", "rear", "left", "right", "middle", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (5)
1. The utility model provides a directional drilling section pipeline anticorrosive coating insulating properties evaluation device that passes which characterized in that: the device comprises a first measuring mechanism, a second measuring mechanism, a direct-current power supply, a current interrupter and a temporary auxiliary anode, wherein the first measuring mechanism is installed at a first end of a crossing section pipeline, the second measuring mechanism is installed at a second end of the crossing section pipeline, the first measuring mechanism is used for acquiring an electrifying potential and an outage potential of the first end and an electrifying current and an outage current flowing through the first end, the second measuring mechanism is used for acquiring an electrifying potential and an outage potential of the second end and an electrifying current and an outage current flowing through the second end, a negative pole of the direct-current power supply is connected with a non-crossing section pipeline connected with the second end of the crossing section pipeline, a positive pole of the direct-current power supply is connected with the current interrupter, and the current interrupter is connected with the temporary auxiliary anode.
2. The insulating property evaluation device of the corrosion protection layer of the directional drilling crossing segment pipeline according to claim 1, characterized in that: the first measuring mechanism comprises a first voltmeter, a first reference electrode and a first clamp-on ammeter, the positive electrode of the first voltmeter is connected with the first end of the pipeline at the crossing section, the negative electrode of the first voltmeter is connected with the first reference electrode, the first reference electrode is in contact with the ground, the first clamp-on ammeter comprises a first measuring clamp and a first ammeter body which are connected with each other, and the first measuring clamp is arranged at the first end of the pipeline at the crossing section in a surrounding mode.
3. The device for evaluating the insulating property of the anticorrosive coating of the directional drilling through section pipeline according to claim 2, characterized in that: the second measuring mechanism comprises a second voltmeter, a second reference electrode and a second clamp ammeter, the positive electrode of the second voltmeter is connected with the second end of the pipeline at the crossing section, the negative electrode of the second voltmeter is connected with the second reference electrode, the second reference electrode is in contact with the ground, the second clamp ammeter comprises a second measuring clamp and a second ammeter body which are connected with each other, and the second measuring clamp is arranged at the second end of the pipeline at the crossing section in a surrounding mode.
4. A method for evaluating the insulating property of a directional drilling through-section pipeline anticorrosive coating by using the evaluation device of any one of claims 1 to 3, is characterized by comprising the following steps of:
(1) starting the direct current power supply and switching on and off the current interrupter,
(2) acquiring electrified potential V of the first end of the pipeline passing through the section through a first measuring mechanism 1on Power-off potential V 1off Conduction current I 1on And a power-off current I 1off (ii) a Acquiring the electrified potential V of the second end of the pipeline passing through the section through a second measuring mechanism 2on Power-off potential V 2off Conduction current I 2on And a power-off current I 2off ，
(3) To the electrified potential V of the first end of the pipeline of the crossing section 1on And a power-off potential V 1off Differencing to give Δ V 1 ＝V 1on -V 1off To the electrified potential V of the second end of the crossing section pipeline 2on And a power-off potential V 2off Differencing to give Δ V 2 ＝V 2on -V 2off Then to Δ V 1 And Δ V 2 Averaging to obtain the difference between the average power-on potential and the power-off potential of the pipeline passing through the segment
The electrified current I to the first end of the pipeline passing through the section 1on And a power-off current I 1off Differencing to give Δ I 1 ＝I 1on -I 1off Current I to the second end of the pipeline passing through the section 2on And a power-off current I 2off Differencing to give Δ I 2 ＝I 2on -I 2off Then to Δ I 2 And Δ I 1 Obtaining the current leakage I of the pipeline passing through the section by difference sect ＝ΔI 2 -ΔI 1 ，
(4) Obtaining the average resistance of the anticorrosive coating of the pipeline at the crossing section according to ohm's law
(5) The average surface resistivity r of the anticorrosive coating of the pipeline at the crossing section is calculated by using the following formula sect And resistivity r for evaluation under the condition of conversion of 1000 Ω & cm sect@1000Ω·㎝ ，
r sect ＝R sect ×A s
A s ＝πdL
Wherein ρ is test D is the outer diameter of the pipeline at the crossing section, L is the length of the pipeline at the crossing section,
(6) then calculating to obtain the average conductivity of the anticorrosive coating of the pipeline at the crossing section
(7) According to the average conductivity or resistivity r of the anticorrosive coating of the pipeline at the cross section sect@1000Ω·㎝ And determining the insulating property of the anticorrosive coating of the pipeline at the crossing section.
5. The method for evaluating the insulating property of the anticorrosive coating of the pipeline at the crossing section of the directional drill according to claim 4, characterized by comprising the following steps of: said step (3)Ratio of potential difference of medium and cross section pipeline
And (3) the K value is between 0.625 and 1.6, otherwise, the pipeline at the crossing section is divided into more than two sub-crossing section pipelines, and then the insulating property of the anticorrosive coating of each sub-crossing section pipeline is evaluated according to the steps (1) to (7).
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| CN202210747894.5A CN115113007A (en) | 2022-06-29 | 2022-06-29 | Device and method for evaluating insulating property of anticorrosive coating of pipeline at crossing section of directional drill |
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| CN202210747894.5A CN115113007A (en) | 2022-06-29 | 2022-06-29 | Device and method for evaluating insulating property of anticorrosive coating of pipeline at crossing section of directional drill |
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